A disk device, for example a magnetic disk device, includes a magnetic head and a carriage assembly. The magnetic head reads/writes data to/from a magnetic disk. The carriage assembly supports the magnetic head in a movable manner with respect to the magnetic disk. The magnetic head has a slider attached to a suspension, and a head part provided in the slider. The head part is configured to include a recording head for writing and a reproducing head for reading.
In recent years, a magnetic head for perpendicular magnetic recording has been proposed to further increase the recording density and capacity of the magnetic disk device and reduce the size thereof. In a magnetic head of this type, a recording head has a main magnetic pole, a trailing shield, and a coil. The main magnetic pole generates a perpendicular magnetic field. The trailing shield is arranged on a trailing side of the main magnetic pole with a write gap interposed between the main magnetic pole and the trailing shield, and closes a magnetic path between the magnetic disk and the trailing shield. The coil serves to pass a magnetic flux through the main magnetic pole. A high frequency oscillator (high frequency assist element) has been proposed that is disposed between a medium side end part of the trailing shield and the main magnetic pole, and the high frequency assist head in which a current flows to the high frequency oscillator through the main magnetic pole and the trailing shield to oscillate.
With the high frequency assist head having such high frequency oscillator, magnetization reversal of the medium recording layer occurs easier due to the high frequency oscillation by the high frequency oscillator, which advantageously improves the ability to record. However, a structure in which a magnetic pole includes a built-in high frequency assist element also has an effect in which a magnetic field in an opposite direction to recorded signals is intensified directly under the trailing shield in the vicinity of the write gap. The oppositely-directed magnetic field may deteriorate recorded-signals.